FR2714398A1 - Network of glass threads and composite material reinforced by said network. - Google Patents

Abstract

The present invention relates to a network of parallel glass threads intended to serve as a reinforcement for an organic material and the resulting composite material. This network consists of a multiplicity of continuous glass threads arranged in parallel in the form of a flat sheet, said threads being linked to each other by threads arranged transversely to said sheet according to a binding method called chain, the the smallest interval between two consecutive binding threads being about 5 millimeters, the binding threads having a modulus of elasticity lower than that of the glass threads. Application to the production of parts subjected to mechanical forces.

Description

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  NETWORK OF GLASS WIRES AND COMPOSITE MATERIAL

REINFORCED BY THIS NETWORK

  The present invention relates to a network of parallel glass wires for

  serve as reinforcement of an organic mixture.

  Glass strands can be used in many ways to reinforce thermosetting or thermoplastic organic materials. When a part obtained from such reinforced material is mechanically stressed during its use, it is known to produce said piece from glass son oriented in a preferred direction. Often this type of piece is made by impregnating material

  organic several layers superimposed oriented glass threads.

  The level of mechanical properties of such a part is due in large part to the quality of the adhesion between the reinforcing glass threads and the material

  surrounding organic matter, as well as the possible bonding of the layers of wires between them.

  Thus, Japanese patent application JP-55-117 649 recommends binding, in whole or in part, a series of flat layers of parallel glass son by means of a wire which passes through all of said layers perpendicular to the plane. defined by each layer. By this means, the shear strength of such a part subjected to a

  bending force is improved.

  This mode of association of reinforcement and organic matter is of interest

  for producing simple parts, such as leaf springs.

  The realization of a complex piece, in which the reinforcements arranged in parallel are oriented in a plane in at least two different directions

  to follow the shape of said piece, presents particular difficulties.

  Indeed, such a part requires the juxtaposition of at least two layers of

  parallel reinforcements in two different orientations.

  This distribution of reinforcement results in a discontinuity when one passes from one sheet to another. If the zone in which this discontinuity is located, whether on the surface or within the composite material, is subjected to forces, over-stressing will appear in this zone with the consequent risk of rapid degradation of the material. On the other hand, the different orientations of the tablecloths

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  reinforcement also induce overstress over the entire periphery of the piece

composite material.

  The present invention relates to an arrangement of parallel glass son such that said son can be used as reinforcements in a complex room, avoiding any discontinuity within said room. The subject of the present invention is an arrangement of parallel glass wires in which the method of bonding said wires to one another is such that it practically does not affect the fatigue strength of a composite part in which said arrangement serves as reinforcement. , and that it allows the orientation changes of said glass threads within

said room.

  The present invention also relates to a reinforced composite material

  by such an arrangement of parallel glass son.

  These objects are achieved by means of a network of glass threads consisting of a multiplicity of continuous glass threads arranged in parallel in the form of a flat sheet, said threads being connected to each other by threads arranged transversely to said sheet according to a binding method called chain, the smallest interval between two consecutive connecting son being about 5 millimeters, said connecting son

  having a modulus of elasticity lower than that of glass yarns.

  One of the advantageous characteristics of the network of glass yarns according to the invention is its ability to be deformed, for example in a plane, so as to inflect the orientation of the glass yarns constituting the sheet in a given zone. This change of direction is effected, for all the son of the web, relative to one of the transverse son that bind said son. For convenience, these threads

  transversals will be called in the following description link son.

  During the production of a composite material reinforced by a network of parallel glass son of the type of that of the invention, these bonding wires, when made of glass, considerably lower the fatigue strength of this material, because of transverse orientation effects with respect to the main direction of solicitation

mechanics of the material.

  Such a phenomenon is markedly reduced when the bonding wire consists of a material whose elastic modulus is less than that of glass, and that all

  better than this module approaches that of the organic matrix.

  The binding mode of the son of the web of the network according to the invention is a chain and, preferably, a chain with closed meshes. This method of bonding by a chain allows the son of the glass sheet to be held within it, stretched and without undulations which allows to significantly increase the resistance in

  fatigue of a composite material consisting of such a reinforcement.

  On the other hand, this binding method makes it possible to maintain a constant and defined spacing between the glass threads of the sheet in order to ensure a good flow of the resin.

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  organic within the reinforcement during the molding phase for obtaining the composite material. Finally, this binding method, by its cohesion, avoids any risk of random movement of the strands of glass son during the molding phase when the injection pressure or compression becomes high, which improves the

  reproducibility of castings.

  The yarn chosen as the binding yarn or chain is preferably an organic yarn.

  When the yarn network according to the invention is intended to reinforce a determined organic material, the binding yarn or chain may consist of an identical material or

similar.

  The deformability of the glass yarn network according to the invention is closely dependent on the interval separating two consecutive connecting threads or chains. To obtain an inflection of the sheet of son parallel in a plane, without causing folds or ripples, it is preferable that the smallest interval between

  two consecutive connecting son is at least equal to 5 millimeters.

  The connection wires in the wire network according to the invention are generally

regularly spaced.

  In the yarn network, the glass yarns can be distributed in the sheet in the form of a series of locks, each lock being formed by the meeting of several

son.

  In the context of the invention, the tows forming the web have a title of at least 300 tex. The glass threads, distributed or not in the form of locks, are themselves made up of a multiplicity of continuous filaments whose average diameter is at least

equal to 10 micrometers.

  The yarn network according to the invention is used to reinforce thermosetting or thermoplastic organic materials. Composite material made

  comprises at least one layer of such a network.

  In this material, the layer or layers of threads which reinforce it may each consist of a network according to the invention, the ply of which is deformed with respect to at least one connecting thread, so that the threads are distributed in at least two

  groups of parallel wires forming a definite angle between them.

  In the composite material, each sheet of parallel son can be deformed while remaining in a plane, each wire or wick forming said sheet having been rotated about each axis perpendicular to said sheet and passing into the contact zone between said wire or said wick and the connecting wire chosen as deformation axis. The manipulation of the glass sheet, the deformation of the network of parallel glass son associated with it and the preservation of this deformation are greatly facilitated by the deposition of an organic material, liquid or in the form of

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  powder on the surface of the tablecloth. The quantity of organic matter deposited is

  generally greater than 0.5% by weight of the web.

  For convenience, this organic deposit material will be referred to in the following

description "binder".

  The binder is deposited at a temperature below its softening or melting temperature and reheated to the surface of the web to a temperature above its softening or melting point to ensure adhesion of the binder to the surface of the tablecloth. Softening means the passage of the solid phase to a sufficiently viscous phase to ensure adhesion of the binder to the web. The softening or melting temperature of the binder is generally

greater than 40 C.

  After cooling and return below this softening or melting temperature of the binder and the web, the latter has a state of consolidation such that its handling is greatly facilitated. By consolidation means a state such that the intrinsic characteristics of the network of parallel glass son and the deformed web are not altered by successive manipulations. Subsequently, the geometric deformation of the network of parallel glass son must occur at a temperature above the softening point or melting of the binder. The network of glass wires thus deformed, after returning to a softening or melting temperature of the binder, also has a state of consolidation such that its manipulation is greatly facilitated and its deformation geometry

easily preserved.

  The advantages of the present invention will be better understood through the example

  described below which is illustrated by a single figure.

  This figure schematically represents a fragment of a network of

glass according to the invention.

  This network consists of a series of roving wicks 10 arranged parallel to each other in a plane. Each wick has a title of 1200 tex and it consists of filaments whose average diameter is of the order of 17 micrometers. The sheet of wicks 10 is held by a closed chain 11 constituted by

  a polyester thread with a title of 50 dTex.

  The locks 10 are interconnected by said chain by using a loom of the knit stitch knit type. The interval "d" between two consecutive chains is 8 millimeters. As shown in the figure, this network may be deformed relative to the chain 12. Staying in a plane the wicks 10 have rotated by an angle and using the loops of the chain 12 as hinges. This change of orientation is made

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  without formation of fold or waviness of the web. The same network can be deformed with respect to several chains to follow complex shapes. Thanks to this great flexibility, the network according to the invention can play the same role as several layers juxtaposed and oriented differently, but without having a discontinuity from one end of the sheet of glass son to another. Thus, a flat plate, curved at its two ends, 70 cm in length and cm in width was made by stacking 10 layers of a network of strands of yarns.

  glass as defined above.

  Each layer is formed of a network of strands of son on which was previously deposited a thermoplastic binder powder. This binder deposited at a rate of 1% by weight of glass is a polyester sold under the reference NEOXIL 940 HF-2B by the company DSM. Deformation of the network is consolidated after a treatment

thermal at 80 C.

  The stack made was impregnated with a resin consisting of a system marketed by THE DOW CHEMICAL Co under the trademarks

D.E.H. 39 and D.E.R. 332.

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Claims (10)

  1. Arrangement of parallel glass son, intended to be associated with an organic mixture for producing a composite material, characterized in that it is formed of a network consisting of a plurality of continuous glass son arranged in parallel in the form of a flat sheet, said son being connected to each other by son arranged transversely to said sheet in a bonding mode called chain, the smallest interval between two consecutive connecting son being about 5 millimeters, the son of   bond having a modulus of elasticity lower than that of glass son.   2. Wire arrangement according to claim 1, characterized in that the wires of   liaison are regularly spaced.   3. Arrangement of wires according to one of the preceding claims, characterized in   that the glass threads are distributed in the sheet in the form of a series of locks,   each wick having a title equal to at least 300 tex.   4. Arrangement of wires according to one of the preceding claims, characterized in   that the glass threads consist of filaments whose average diameter is at less than 10 micrometers.   Wire arrangement according to one of the preceding claims, characterized in that   it consists of a network of son on which was deposited an organic binder.   6. Wire arrangement according to claim 5, characterized in that it is   consisting of a son network on which has been deposited a thermoplastic organic binder.   7. Composite material formed of a thermosetting organic mixture or thermoplastic reinforced with glass son, characterized in that it comprises at least one layer of a glass son network as defined by any one of Claims 5 to 6.   8. Composite material according to claim 7, characterized in that the layer or layers of son that reinforce said material each consist of a network whose sheet of glass son is deformed with respect to at least one connecting wire, way that the wires are distributed in at least two groups of parallel wires making between them a certain angle.   9. composite material according to claim 8, characterized in that the ply is deformed while remaining in a plane, each wire or wick forming said ply having been rotated about each axis perpendicular to said ply and passing in the contact zone between said yarn or bit and the yarn selected as deformation axis.   10. Composite material according to one of claims 7 to 9, characterized in that   it comprises at least two layers of a network consisting of a sheet of glass threads secured by a polyester chain, said layers reinforcing a mixture of epoxy resin base.